A study by NACE International revealed that the annual global cost of corrosion is estimated to be US$2.5 trillion. North Sea oil costs are increasing faster than any other industrial sector but accidental damage and corrosion are major issues affecting the sustainability of the industry.
The constant wet and dry can accelerate the effect on metal degradation; combine this with damage caused by impact or abrasion and the result is extensive maintenance costs affecting both operational and capital expenditure. “In a time where the sustainability of the global petroleum industry is under question, it has become key for businesses to react to structural damage to protect the integrity of offshore assets and reduce the cost of maintenance in order to stay profitable,” comments Ed Hall, managing director at Oxifree Global.
Corrosion is the deterioration of metal when it comes into contact with oxygen and water in the environment, however this reaction can be accelerated by many other factors. Onshore refineries have to contend with UV rays, harsh climate conditions plus chemical splash and fumes degrading the metal structures; in the desert, it’s the UV rays and humidity mixed with high chloride content in the sand. Offshore, corrosion is accelerated by the salt, wind, rain and wave slam combined with a build-up of chlorides, which create the perfect electro-chemical environment.
Corrosion plays a critical role in the integrity of pipelines and structural integrity. It affects every metal component at each stage of its life leading to health and safety and ecological risks, which pose considerable ongoing challenges for the industry.
It can quickly develop around complex geometric shapes like the connections between pipes, within the crevices of bolts and nut heads, on and around welding and between flange face and valve fittings. The non-uniform shape of these components pose difficulties for providing adequate protection against corrosion.
It is even more of an issue for moving components like valve stems, actuators and pumps, which are vital to operation. In some cases dissimilar metals lead to galvanic corrosion and the traditional methods of protection including paint and wax tape, will not stop the onset of this or corrosion creep.
“Protecting metal components is essential if owners want to extend the lifespan of their assets and make considerable cost savings,” explains Ed. Left alone, corrosion can lead to serious health and safety and environmental risks including leaks, which incur considerable penalties.
Whether assets are based in the sand and blistering heat of the Middle East or situated in an offshore marine environment, corrosion leads to increased maintenance costs, affecting operational and capital expenditure. And so, preventing corrosion is a vital step for asset owners worldwide.
Areas where two pieces of metal join are particularly susceptible to corrosion and effective monitoring of these areas is essential, but the complex shape of areas like flanges, nuts and bolts provide challenges when sourcing adequate protection.
Historically, the standard treatment of corrosion has been to apply paint but this is not always a reliable solution – it requires time and cost consuming surface preparation to meet the industry standard, is highly susceptible to humidity levels during application and chips easily, and exposes the asset underneath. Another treatment for the protection of complex metal assemblies has been that of petrolatum tape for wrapping around the asset, but this requires ancillary products and can be time consuming to apply and difficult to remove for maintenance.
What is the solution to corrosion?
The total annual US cost for protective coatings is US$108.6 billion. 50% of all corrosion costs are preventable, and approximately 85% of these are in the area of coatings.
Thermoplastic is one of the most recent developments on the market for the protection of metal components, which asset owners worldwide are embracing and saving millions.
Thermoplastic coatings are an alternative, sophisticated coating solution to corrosion and contamination and have been proven to extend the lifetime of assets. They require minimal surface preparation, have far less reactivity to climatic conditions during application, and can be applied to live components, therefore greatly reducing operating costs.
Leading the fight against the global corrosion epidemic is Oxifree Global, which has developed Oxifree TM198, a protective thermoplastic coating which prolongs the life of metalwork and in turn provides significant savings for asset owners.
“Previously, operators had no choice but to accept that assets would have to be replaced regularly,” explains Ed. “Oxifree TM198 is a patent protected, organic, self-lubricating coating for the protection of metal components. It contains organic corrosion inhibitors, is reusable during application and provides immediate protection.”
TM198 lasts several years and has been proven to extend the lifecycle of components, reducing maintenance costs by at least 40%. It can be applied to pipelines and joints but is particularly effective for complex geometric areas like flanges, which have fastenings that have to be accessed and used again in the future.
Unlike other thermoplastic coatings, TM198 secretes a natural inhibiting oil to encapsulate the component without adhesion, acting as a secondary barrier against contaminants, this protective technology allows the freedom for the protected asset to move.
Whilst other solutions take hours to apply and dry, the advantage of TM198 is that it can be applied in a tenth of the time compared to paints and tapes and it cools on impact within moments, allowing equipment to maintain live function, sometimes even during application. It can easily be cut away for inspection of the substrate, then filled in.
Companies worldwide have been saving millions through investment in Oxifree Global’s patent protected thermoplastic coating. Oxifree recently worked with an oilfield in Vietnam and identified more than 2000 flanges, which were flagged as high priority and in urgent need of protection against further corrosion due to the highly corrosive environment. Technicians were able to coat up to 50 flanges each day and over the course of two months, a total of 2128 flanges were protected, offering a long-term anti-corrosion solution and reduction in maintenance costs.
Oxifree Global is also able to offer a second layer of protection in the form of Oxitape, an abrasion and impact resistant shell. It can be applied on top of TM198 and is particularly effective for use in the splash zone in the coastal/offshore environment. This area can be subject to severe corrosion through salt exposure, tidal effects, wave slam, impact from floating debris and even from work vessels, causing damage to existing corrosion control methods. The metal surfaces of the risers are then left exposed once again to the elements. However, Oxitape is able to withstand these impacts, protecting the TM198 underneath and continuing asset protection.
It also offers protection against equipment to be buried under ground, which is susceptible to abrasion from gravel, rocks and sand. Combining the two ensures a level of protection not available with traditional tapes and paints. Both are easily removed, making it easy to conduct interim inspections and maintenance.
Ed comments: “We are dedicated to providing an effective way for the oil industry to reduce the costs of corrosion and accidental damage. The combination of TM198 and Oxitape combined with the new Service Gun (SG1) provides asset owners with a comprehensive cost saving solution.”
For interim inspections, areas of TM198 and Oxitape, which have been cut away can be refilled as newly applied material will bond to the existing coating. The Polymelt SG1 provides a compact, lightweight tool for making these small coating touch-ups in the field. It can be operated by the end user and doesn’t require a technician to be sent to site, making inspections and maintenance in the field easier and contributing to a more cost effective operation for asset owners.
Limiting the cost corrosion in oilfield
A proactive approach to protecting metal is already making significant savings for Oxifree Global’s clients. Ed says: “Insufficient funding can be a reason asset owners don’t prioritise preventative maintenance but, in the long run, it is this that will save the industry billions.” Applying coatings in stages can help to maintain asset integrity and manage the costs associated with applications at the same time.
Whilst it may be impossible to prevent corrosion itself, it is possible to provide long-term protection to reduce the need for continual renewal of metal components. A thermoplastic coating, combined with protective tape will prolong the lifespan of asset components, reducing expenditure and the cost of both shutdowns and unscheduled maintenance caused by corrosion and accidental damage.
Adapted by David Bizley
Read the article online at: https://www.oilfieldtechnology.com/drilling-and-production/18082016/reducing-the-impact-of-corrosion-with-thermoplastic-coatings/